New Iron Deficiency Guidelines Set Higher Ferritin Thresholds for Diagnosis

The American Society of Hematology (ASH) has introduced new clinical guidelines recommending higher ferritin thresholds to diagnose iron deficiency, aiming to help healthcare professionals identify depleted iron stores earlier and reduce the number of cases that go unrecognized.

Published in September 2026, the recommendations address differences in diagnostic practices across patient populations, including children, adults, menstruating individuals, pregnant people and patients with inflammatory conditions. The guidance establishes specific thresholds intended to support clinical decisions rather than relying solely on traditional laboratory reference ranges.

Iron deficiency occurs when the body does not have sufficient iron to meet its needs. It can develop before a person has anemia, meaning that a diagnosis based only on low hemoglobin levels may fail to identify some people with depleted iron stores.

What the New Guidelines Recommend

The updated guidance sets different ferritin thresholds according to age, physiological status and underlying health conditions.

Ferritin is a protein that stores iron in the body. Measuring ferritin in the blood helps clinicians assess iron reserves, although inflammation and certain medical conditions can affect the results.

The ASH recommendations include the following thresholds:

• Children aged 9 months to 4 years: A ferritin level of 20 nanograms per milliliter (ng/mL) or lower.
• Adults who are not menstruating or pregnant: A level of 30 ng/mL or lower.
• Menstruating individuals: A level of 30 ng/mL or lower.
• Pregnant individuals: A level of 30 ng/mL or lower.
• People with heavy menstrual bleeding or certain other risk factors: A threshold of 50 ng/mL or lower may be appropriate.
• Pregnant individuals with anemia: A threshold of 50 ng/mL or lower may be appropriate.
• Adults with inflammation: Ferritin below 100 ng/mL or transferrin saturation below 20% may indicate iron deficiency.

These thresholds are not interchangeable. The appropriate interpretation depends on the patient's circumstances, symptoms, risk factors and other laboratory findings.

Why Ferritin Thresholds Are Changing

One of the main reasons for the updated guidance is that traditional diagnostic cutoffs may fail to identify some people whose iron stores are already insufficient.

Earlier thresholds commonly used for adults were around 15 ng/mL, while the new ASH guidance suggests a threshold of 30 ng/mL for many adult groups.

The higher cutoff is intended to improve the recognition of iron deficiency before it progresses or becomes more difficult to identify. People whose results previously fell above an older diagnostic threshold may now meet the criteria for further clinical evaluation.

ASH developed the recommendations through a multidisciplinary guideline panel that reviewed available evidence and used the GRADE framework to assess recommendations. The panel also identified gaps in the existing research, meaning that some recommendations are based on evidence with limited certainty.

Iron Deficiency Can Occur Without Anemia

Iron deficiency and iron-deficiency anemia are related but distinct conditions.

Iron deficiency means the body's iron stores are insufficient. Iron-deficiency anemia develops when inadequate iron contributes to a reduction in hemoglobin, the protein in red blood cells responsible for carrying oxygen.

A person may have depleted iron stores before their hemoglobin level falls enough to meet the criteria for anemia. This distinction is important because relying on hemoglobin alone can miss iron deficiency at an earlier stage.

Potential symptoms include fatigue, weakness, dizziness and difficulty concentrating. However, these symptoms can have many causes and cannot establish an iron-deficiency diagnosis without appropriate clinical assessment.

The updated guidance encourages clinicians to consider iron status directly rather than treating the absence of anemia as proof that iron stores are adequate.

Why Inflammation Complicates Diagnosis

Ferritin testing can be more difficult to interpret in people with inflammation.

Ferritin levels may increase during inflammatory responses, even when the body's available iron is insufficient. As a result, a ferritin result that appears relatively high does not always rule out iron deficiency in someone with an inflammatory condition.

For adults with inflammation, the ASH guidance recommends evaluating serum ferritin alongside transferrin saturation, a measure that helps indicate how much circulating iron is available for use.

Under the recommendations, iron deficiency may be considered when ferritin is below 100 ng/mL or transferrin saturation is below 20%. Clinical interpretation remains necessary, particularly for people with conditions such as inflammatory bowel disease, infections or cancer.

What the Changes Mean for Healthcare Providers

The updated thresholds could affect how clinicians interpret blood tests and decide whether additional evaluation is appropriate.

Laboratories often display reference ranges based on the distribution of results in a population. Such ranges do not always correspond directly to the levels used to make clinical decisions about a particular condition.

ASH is encouraging healthcare institutions to consider adopting evidence-based diagnostic thresholds so that iron deficiency is identified more consistently across laboratories and healthcare settings.

Implementation may take time, however. The publication of a guideline does not automatically mean every laboratory or healthcare provider has changed its testing reports or diagnostic procedures.

The recommendations also do not mean that everyone with a ferritin result near a threshold requires the same treatment. Clinicians must consider the full clinical picture and investigate potential causes of iron deficiency.

What Patients Should Know

The revised guidelines may help patients understand why a ferritin result should be interpreted in context rather than viewed only through a laboratory's general reference range.

People experiencing persistent symptoms or having known risk factors for iron deficiency can discuss appropriate testing with a qualified healthcare professional. Ferritin measurements may be considered alongside a complete blood count and other iron studies when clinically appropriate.

A higher diagnostic threshold does not mean patients should self-diagnose or begin taking iron supplements without medical guidance. Excess iron can be harmful, and treatment decisions depend on the cause of the abnormal results and the individual's medical circumstances.

ASH has also indicated that additional guidance on treating iron deficiency is anticipated in 2027. The September 2026 publication focuses on diagnosis rather than establishing a single treatment approach for every patient.

Conclusion

The American Society of Hematology's 2026 guidelines introduce higher ferritin thresholds intended to improve the diagnosis of iron deficiency across several patient groups.

By distinguishing iron deficiency from iron-deficiency anemia and accounting for the effects of inflammation, the recommendations aim to help clinicians recognize low iron stores earlier.

The next challenge is implementation. Consistent use of the updated thresholds, appropriate clinical interpretation and further research will help determine how effectively the recommendations improve diagnosis and patient care.

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